Recycling multilayer plastic packaging is challenging due to their intrinsic compositional heterogeneity. A promising route to increase recycling rates for these materials is delamination which allows recycling the polymers separately. Yet, this process is not well fundamentally understood. This study aims to obtain first principles-based insights of the delamination mechanism of multilayer flexible packaging film (MFPF) with carboxylic acids. Delamination of MFPFs was described through a model based on Fick’s first law of diffusion and first-order dissolution kinetics of polyurethane (PU) adhesives. The model was experimentally tested on 5 different MFPFs at different temperatures (50-75 °C), formic acid concentrations (50-100 v%) and solid/liquid (S/L) ratios (0.005, 0.025 and 0.12 g/mL). Under the studied conditions the model proved to successfully estimate the delamination time of MFPF with the average Theil’s Inequality Coefficient (TIC) value of 0.14. Essential for scalingup delamination processes is that it is possible to use high S/L ratios as the solubility of the adhesive is rarely limiting.

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